This work is undertaken to investigate the use of vanadyl ion, VO2 ion, electron paramagnetic resonance spectroscopy as a probe of metal binding sites in proteins. Work is focusing on the iron transport protein human serum transferrin. Studies of Fe3 ion, VO2 ion binding to transferrin in single crystals and solutions will be undertaken to examine the nature of the two metal sites. Computer simulation techniques will be developed to aid in understanding the EPR spectrum of iron transferrin.